It has been known that halogen-containing organic polymers, especially vinyl chloride polymers, are not stable under the action of heat, light and weathering and are subject to deterioration or degradation. Numerous chemicals and chemical compositions have been proposed to combat these adverse effects. For the most part, these stabilizers have been directed toward stabilization of the polymer against heat encountered during processing of the polymer and its fabrication into articles. In addition, in order to satisfactorily process the polymer it has also been necessary to employ lubricants, such as external and internal lubricants.
For example, in U.S. Pat. No. 3,644,246, issued Feb. 22, 1972, to M. Lozemou, it has been proposed to use a metal salt of a monoalkyl ester of an unsaturated dicarboxylic acid in combination with an organotin carboxylate as a composition for lubricating heat and light stabilization of chlorine-containing polymers.
Additionally, in U.S. Pat. No. 3,578,621, issued May 11, 1971, to C. Stapfer, and U.S. Pat. No. 4,111,889, issued Sept. 5, 1978, to Kaneko et al, it is suggested that diesters of both saturated and unsaturated diacids be employed as lubricants for halogen-containing polymers.
In practice, however, it has been recognized that the diesters of unsaturated dicarboxylic acids, such as distearyl maleate, while providing some degree of stabilization to the polymers, also produce undesirably poor lubrication properties, particularly undesirably poor fusion time properties.
On the other hand, the metal salts of monoesters of unsaturated dicarboxylic acids, while providing a good degree of lubrication properties to the polymers, are quite poor stabilizers and produce undesirable yellowing in the polymer.
It would be highly desirable if the good lubrication properties could be obtained in halogen-containing resins without producing the highly undesirable yellowing of the polymer compositions. Likewise, it would be highly desirable to obtain good stabilization effects in the polymer compositions without adversely affecting the lubricating properties, particularly the fusion time characteristics, of the polymer compositions.